Hello People,
OK, here goes, it's a long shot but I'm hoping that someone who has experience with my model of bike will have some answers, or at least pointers.
I'm in the process of turning a 1986 Honda CBX250RSD into a cafe racer/tracker custom thingy.
Ive done many cosmetic things to it and it's starts and runs well, but only when I short the solenoid.
I'm tested all the handlebar switches, solenoid, ignition switch, solenoid, clutch switch, and they all appear to be working correctly. I have a workshop manual and Ive run out of things to check now.
Theres a couple of odd things that may help with the diagnosis. When I press the starter button with the front brake lever pulled in the brake light dims.
I know there is a "safety" circuit on this model that stops the starter motor from turning if the bike os in gear without the clutch pulled in and I am picking it has something to do with this?
Also, when I turn on the indicators, left or right, they all flash at once. I'm not overly worried about that for now, but thought it may have something to do with the issue.
I know these weird electrical issues are almost impossible to diagnose remotely, I was just hoping someone may have been in this situation before.
Cheers,
Andrew

Fist up...welcome.
With the indicators, have you fitted LED aftermarket indicators? If so the dash light for the indicators could well be the culprit for them all flashing at once...

As for starter issue... sounds very much like there is a wrong connection somewhere.. especially if the brake light dims when hitting the starter...
Are you using the standard loom?? Have you made and modifications to the loom??
Checked all the earths etc....
The Clutch safety switch can be bypassed (connect the 2 wires together)... is there a side stand switch on that model?

I am sure there are plenty of others on here with much more sensible info for you... good luck... and remember... sometimes it pays to walk away for a couple of hours and do something else... then return to the problem

Thanks Andy,
Yes, I have fitted after market LED indicators and a new flasher unit designed for LED's. It plugs straight in. I swapped it out with the standard one just to be sure and got the usual too fast flash. What's with the dash light? The background dash light comes on, but that's about the only signs of life in the dash.
Why would the indicator dash light make them all flash at once?
I've got two sets of stock clocks (I'm making one bike out of two), and neither of them seem to do much. No neutral light or rev counter. I have some after market clocks to fit later but wanted to use the stock ones to start with until I figure out what wires go to what bits. Everything was very weathered, the bikes sat outside for I'm guessing around 10 years at the wreckers.
I'm using the stock loom, no modifications to it. Everything plugged in to the right colour coded wires, nothing left unplugged, it all matched up nicely. The only wires I had left where for the fuel tank gauge, so I plugged the old sender in just to be sure that it wasn't that.
Good idea about the side-stand switch, I don't think that model has one, certainly not fitted to mine, but I will check the documentation to be sure if it should have one.
I tried bypassing the clutch switch, connecting the two wires together but it didn't make any difference, I've left them connected for now to eliminate any possibility of that being the problem.
I have a spare stock loom that I may swap to and see what that does.
As far as I can tell there is just one big earth that goes from the battery to the engine. There didn't seem to be any other earths that I could find. I'm going to have a really good study of the wiring diagram to see what may be going on, but electrics are not by forte, I'm a mechanical engineer and I knew the electrics were going to give me grief ;-)
On a more positive note, I did short the solenoid and have a go on it.
Video is here:

OK... I am now an expert on LED Indicators..lol.
I have attached a pdf which will explain them all flashing... but the easy way to check is to remove the dash bulb for the flashers... they should now work correctly..

There should be a starter relay as well as the solenoid... chase that down and see if you are getting power to that.. I did notice on the video there was a lot of corrosion around the starter solenoid..and the connection appears badly weathered... it will most likely be a crook connection or connections somewhere along the way... and I agree with you... Electrics are White Mans Magic...

Welcome to the forum Andrew,
Have a look at Andys' Across indicator thread
It should help you with your indicator issue, sound's like you need to add a couple of diode's to the indicator dash warning light

Try using a multimeter on your earth lead, set it to 200 Ohm's and put one lead from the meter to each end of the earth lead, it should have a very low resistance.
Check for any corrosion where the wire is crimped onto the cable end's as well.
You might need to add in another earth somewhere to ground the engine to the frame, both end's need to go to clean bare metal, smear some dielectric grease on the bare metal to stop corrosion too
Also check the regulator/rectifier's earth, they can be grounded to the frame or through one of the wire's coming from it.
Usually the frame isn't bare metal under where the reg/rect mount's, cleaning the paint off may help.
And check the wiring terminal's in the plug for the reg/rect, they can get corrosion on them and cause issue's.
Fuse's should be checked for any sign's of corrosion, add some dielectric grease there
And any relay's too, might pay to smear some more grease on the terminal's

Is the battery new? or at least measuring 12.6V
With the engine running you want close to 14V +/- .2V, measured across the positive and negative battery terminal's

With you finding all the switch's are good, one still may have a dirty connection inside, most switch's can be pulled apart and the contact's cleaned, then just smear some dielectric grease on them to prevent any corrosion from moisture and bad connection's from dust etc.

OK... I am now an expert on LED Indicators..lol.
I have attached a pdf which will explain them all flashing... but the easy way to check is to remove the dash bulb for the flashers... they should now work correctly..

There should be a starter relay as well as the solenoid... chase that down and see if you are getting power to that.. I did notice on the video there was a lot of corrosion around the starter solenoid..and the connection appears badly weathered... it will most likely be a crook connection or connections somewhere along the way... and I agree with you... Electrics are White Mans Magic...

Click to expand...

Thanks Andy, that is very useful information. I'll have another fiddle with it tomorrow (if the weather improves) and report back.

Welcome to the forum Andrew,
Have a look at Andys' Across indicator thread
It should help you with your indicator issue, sound's like you need to add a couple of diode's to the indicator dash warning light

Try using a multimeter on your earth lead, set it to 200 Ohm's and put one lead from the meter to each end of the earth lead, it should have a very low resistance.
Check for any corrosion where the wire is crimped onto the cable end's as well.
You might need to add in another earth somewhere to ground the engine to the frame, both end's need to go to clean bare metal, smear some dielectric grease on the bare metal to stop corrosion too
Also check the regulator/rectifier's earth, they can be grounded to the frame or through one of the wire's coming from it.
Usually the frame isn't bare metal under where the reg/rect mount's, cleaning the paint off may help.
And check the wiring terminal's in the plug for the reg/rect, they can get corrosion on them and cause issue's.
Fuse's should be checked for any sign's of corrosion, add some dielectric grease there
And any relay's too, might pay to smear some more grease on the terminal's

Is the battery new? or at least measuring 12.6V
With the engine running you want close to 14V +/- .2V, measured across the positive and negative battery terminal's

With you finding all the switch's are good, one still may have a dirty connection inside, most switch's can be pulled apart and the contact's cleaned, then just smear some dielectric grease on them to prevent any corrosion from moisture and bad connection's from dust etc.

Click to expand...

Thank you for that information. I will do some earth testing tomorrow if the weather improves. I think you may be on to something about the earth. The headlight doesn't work either. I've replaced the fuses and checked the diode in the fuse box and also replaced the headlight bulb. The battery is new, fully charged. I'll check that the bike is charging it when it's running. I am thinking that I really should clean up all the connectors, they are all a bit corroded. Despite the corroded appearance of the solenoid, it does work, I put 12 volts across a couple of the connector pins (as per the service manual test) and it worked, cranked the engine. Thanks Again.

OK people, RESULT! with the help of my beloved we got it all sorted today. I swapped out the loom for the spare I had, it appeared that someone had meddled with the loom that was on it. Also swapped out the LH handlebar switch assembly as the connections on that were messed with. With the new loom the engine cranked on the button, but no spark. Searched around with a multi meter for a while and found the ignition pick up was not connected properly, cleaned that up and voila, all good. We fitted the stock clocks and got them working, then removed them, figured out what wires went where and then wired in the new clocks. The new clocks have an LED turn signal, which stopped the issue with all the indicators flashing at once. All I need to do now is solder all the connections to the new clocks properly and heat shrink wrap them. I used as much of the cabling from the stock clocks so I retained the big multi plug so they are easy to remove in the future.
Thanks to everyone on here that contributed to solving my issues.
Video of it all sorted here: